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<head>
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    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="root"></div>
    <script src="https://unpkg.com/react@18/umd/react.development.js" crossorigin></script>
    <script src="https://unpkg.com/react-dom@18/umd/react-dom.development.js" crossorigin></script>
    <script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>
    <script type="text/babel">
        class MyComponent extends React.Component{
            constructor(props){
                super(props);
                // this.handleClick = this.handleClick.bind(this);
            }
            
            // handleClick(){
            //     console.log("this:",this);
            // }
            handleClick = (e) => {
                console.log(e.target)
            }
            render(){
                return <div>
                        <input type="button" value="ok" onClick={this.handleClick}/>
                        {/*
                        <input type="button" value="ok" onClick={this.handleClick.bind(this)}/>
                        <input type="button" value="ok" onClick={() => {this.handleClick()}}/>
                    */}

                    </div>
            }
        }

        ReactDOM.createRoot(document.getElementById("root")).render(<MyComponent />);
    </script>
</body>
</html>